Vial autosampler with vial stabilization member

ABSTRACT

A modular vial autosampler has a storage area for vials containing samples to be analyzed and at least one modular sampling station. A vial transfer mechanism includes an arm having a gripper that lifts a sample vial from the storage section, and the arm moves it to a station for identification and then to a sampling station, and under central control activates the sampling station for obtaining a sample for analysis. The vial transfer mechanism gripper is movable in X, Y, and Z directions to capture and move a selected vial and includes an alignment guide for the vials. Potentiometers are used for providing signals indicating arm position and the control is provided with updated information for calibration of the potentiometers and also updated position information for the arm relative to a fixed home position is obtained.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of application Ser. No.08/920,685, filed Aug. 29, 1997, now U.S. Pat. No. 5,948,360 which is acontinuation of application Ser. No. 08/501,198 filed Jul. 11, 1995,entitled AUTOSAMPLER WITH ROBOT ARM, now abandoned which is acontinuation-in-part of application Ser. No. 08/273,537, filed Jul. 11,1994 for MODULAR VIAL AUTOSAMPLER, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to a machine that handles vials containingchemical specimens or samples and moves vials from storage trays to oneor more sample stations on the machine under software control.

Gas chromatographs and similar chemical species analyzers such as massspectrometers are known. Vial handling machines, such as the model 7000Headspace Autosampler sold by Tekmar Co., Cincinnati, Ohio, USA, arealso known. The model 7000 extracts from a covered vial a predeterminedamount of fluid from a static gaseous headspace above a sample, andconveys the predetermined amount of fluid (containing volatiles to beidentified) to a gas chromatograph. Vial autosamplers using dynamicheadspace techniques are also known, such as the model PTA-30W/SAutosampler sold by Dynatech Precision Sampling Corp., Baton Rouge, La.,USA. The model PTA-30W/S routes a purge gas into a covered vialcontaining a sample, and provides an outlet from the vial to carry theexiting fluid (comprising the purge gas and volatile components from thesample) to a separate concentrator trap unit.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a vial handling device comprisesa base unit and a sampling module adapted to mate with the base unit.The vial handling device has a vial storage area on the base unit tohold multiple vials in known locations, and a sampling station in thesampling module where fluid is removed from the vial. The vialtransporter has a controlled arm with a vial gripper for moving a vialbetween the storage area and the sampling station. The sampling modulehas a needle assembly to penetrate the vial to remove the fluid, andmates with the base unit proximate the sampling station. In a preferredembodiment, the base unit has two sampling stations.

The vial transporter arm projects from the base unit along a first (Y)axis, and the main arm is adapted for translation along a second (X)axis substantially perpendicular to the first axis. The vial transporteralso includes a vial gripper head assembly adapted for movement alongthe main arm in the Y axis. The vial gripper assembly includes a gripperhead adapted for translation along a third (Z) axis substantiallyperpendicular to the first and second axes. The position of the gripperassembly and gripper head in the X and Y directions are sensed bypotentiometers which are used to provide position information. Theindicated position of the gripper assembly is calibrated relative to aknown reference such as a fixed home position each time the autosampleris started, or at operator selected times, to insure accuratepositioning of the vial transporter. The travel of the gripper assemblyis sensed with suitable sensors, as disclosed beam interrupters thatwill provide position information relating to a known mechanicalcalibration position on the base unit. The gripper assembly scale alongits X and Y axes between sensed limits is calibrated by determining adigital count from the analog voltage from the position indicatingpotentiometers and correlating that count to the known distance betweenlimits. Software adjustments are made as required to the scale (countsper inch) for the X and Y axes so that the positioning system for thevial transporter stays in calibration.

Additionally, the vial storage area utilizes trays or racks that havereceptacles for the vials to be stored and moved to various stations forthe vials and ultimately to the sampling modules. A calibration systemis utilized in connection with the gripper assembly with positionsensors for determining the orthogonality of the storage trays or racks,using a mechanical sensing bar positioned in each of the racks (tworacks are used preferably) and by determining the actual Y axis locationof an edge of the calibration bar. The position identifiers, such aslook-up tables in a microprocessor or computer that provide the X-Ycoordinates of each of the vial receptacles in the racks, are modifiedto accommodate any slight skewing of the respective rack.

Another aspect of the invention is an improved stabilizing mechanism forthe vials which are held by the gripper head and then lifted and moved.Gripper fingers are used for grasping the neck and cap of the vial, anda stabilizing ring surrounds the main part of the vial as the gripperhead lifts the vial. The stabilizing or guide ring retracts as thegripper head moves to engage a vial in a rack when the vial is to bemoved, to permit gripping the vial and then the ring extends underspring load to surround the vial so that cocking or other misalignmentof the vial relative to the gripper head axis will be reduced oreliminated so that the vial will be properly orientated for placing intoa vial holder station on the base, for example, a sampling station.

A series of sequentially controlled valves, coupled with a syringe typepump provides for the analysis of samples removed from the vials placedin the sampling station.

A vial handling device in the sampling station moves a vial having aspecimen therein from a loading site where it is placed by the gripperhead, to a sampling site, and includes a carrier adapted to hold thevial, an elevator coupled to the carrier, and a mechanism to translatethe carrier laterally as the vial is transported from the loading siteto the sampling site.

In another aspect of the invention, an autosampler device includes abase unit having a port therein, a central control circuit including aremovable circuit module disposed proximate the port, and a panel whichis sized and movably held to the base unit to alternately cover andexpose the port, thereby providing access to the removable circuitmodule through the port.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vial autosampler device in accordancewith the invention;

FIG. 2 is a cut-away view of the device of FIG. 1 along plane 2—2, withonly key components shown and with some components shown in block form;

FIG. 3 is a sectional view of a vial rack along line 3—3 in FIG. 2;

FIG. 3a is a fragmentary end view of a vial rack assembly with partsbroken away to show a thermal block;

FIGS. 4a-4 c are front, side sectional, and top sectional views,respectively, of a first sampling module in accordance with theinvention;

FIGS. 5a-5 c are front, side sectional, and top sectional views,respectively, of a second sampling module in accordance with theinvention;

FIG. 5d is an enlarged sectional view of a vial holder assembly in FIG.5a;

FIG. 6a is a top partial view of a vial transporter according to theinvention;

FIG. 6b is a sectional view taken along line 6 b—6 b in FIG. 6a;

FIG. 6c shows a side sectional view of an end portion of a vialtransporter according to the invention;

FIG. 6d is an enlarged sectional view of a vial gripper and vialstabilizing and guide ring made according to the present invention withparts broken away;

FIG. 6e is an enlarged sectional view of a vial gripper and vialstabilizing and alignment ring taken on a line to illustrate thesupports for the vial alignment ring, with the vial gripper in positionto grip a vial in a storage tray;

FIG. 6f is a view taken along the same line as FIG. 6e with the gripperhead raised and the vial alignment ring in position around the main partof a vial;

FIG. 6g is a sectional view showing the top of the vial alignment ringand taken on line 6 g—6 g in FIG. 6f;

FIG. 7 is a diagrammatic view of a flow path of the device of FIG. 1where only one sampling module is installed;

FIG. 7a is an enlarged schematic representation of a selector valve usedin FIG. 7.

FIG. 7b is a schematic enlarged sectional view of a multi portchromatographic valve used in the flowpath of the present invention.

FIG. 8 is a sectional view of an access panel for a control circuit inaccordance with the invention;

FIG. 9 is a schematic circuit representation for a drive motor circuitfor operation of a robotic arm of the present invention;

FIG. 10 is a flow diagram illustrating the steps of calibrating thepositions of various components of the system; and

FIG. 11 is a flow diagram of the overall control system used with therobotic arm of the present invention.

For convenience, items in the figures having the same reference symbolare the same or serve the same or a similar function.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a perspective view of a vial autosampler device 10 inaccordance with the invention. The device 10 includes a base unit 12that includes a vial storage platform area 14, a vial equilibrationstation 16, a vial identification station 18, separate first and secondsampling stations 20 and 22, and a fluid handling system comprisingvalves, glasswork, and other fluid handling components. Device 10 alsoincludes separate first and second sampling modules 24 and 26 eachdetachably mounted to the base unit 12 at sampling stations 20,22,respectively. Each sampling module 24 and 26 receives a vial containinga specimen and extracts a fluid from the vial for further analysis.Device 10 also includes a vial transporter 28 that carries individualvials between vial storage area 14, vial equilibration station 16, vialidentification station 18, and the first and second sampling stations20,22. Finally, device 10 includes a central programmable controlcircuit that accepts user inputs and controls the operation of device10.

FIG. 2 shows a cutaway view of device 10 as taken along line 2—2 in FIG.1. Vial storage area 14 includes a fixed or stationary platform shapedto receive removable vial racks 30 a, 30 b, which vial racks arepreferably substantially identical. Specimen-containing vials can beloaded into pockets or receptacles 31 of racks 30 a, 30 b at a separatelocation and kept in storage until needed. The racks 30 a, 30 b eachinclude upper portions 29 a, 29 b, and peripheral skirts 33 a, 33 b thatsupport metal cross rods 46 a, 46 b. The rods 46 a, 46 b extend acrossthe racks and are spaced below the upper portions 29 a, 29 b. The rodsalign with each pocket 31 and support the ends of vials placed in thepockets 31. When ready for testing, one or both of the loaded racks canbe lowered into position at vial storage platform area 14. Included invial storage platform area 14 are two push-button switches 32 a, 32 bpositioned on the platform to detect the presence of racks 30 a, 30 brespectively. In each case, the weight of the loaded rack causes therack skirt to depress the push-button to change the state of the switch.

Preferably, the skirts of racks 30 a, 30 b slide down over thermalblocks 48 a, 48 b (one for each rack) which are fixedly mounted to vialstorage platform area 14. The thermal blocks 48 a, 48 b have internalcavities or passageways 49 therein for fluid circulation. The cavities49 are accessible from below the thermal blocks 48 a, 48 b by fittings34,36,38,40. (See FIGS. 2 and 3) Base unit 12 has an input fluid port 41and a drain port 43 connected by internal tubing (not shown) to thefittings for a fluid circuit as follows as shown for thermal block 48 ain FIG. 3: user-supplied fluid, such as tap water, enters port 41 andenters the cavity 49 of the thermal block underneath vial holder 30 athrough fitting 34; the fluid drains via fitting 36 from that cavity andenters the cavity of the thermal block 48 b underneath holder 30 bthrough fitting 38; the fluid then exits the cavity via fitting 40 andleaves device 10 via drain port 43.

Only a few of the vial receiving pockets or receptacles 31 of therack/thermal block combination are shown occupied by specimen containingvials in FIGS. 2 and 3. Vial receiving pockets or receptacles 31 accepteither a vial 42 having a single end cap 42 b or a vial 44 having endcaps 44 b at each end. Vials 44 as shown in FIG. 3, preferably have aliquid retaining, gas porous divider frit 44 d dividing each vial intoupper and lower chambers. Each end cap can be crimped or, preferably,screwed onto the respective vial end. A septum 42 c, 44 c respectively,seals the specimen within the vial.

Each thermal block 48 a, 48 b includes a unitary upper portion 50, alower portion 52, and a gasket 54 sandwiched therebetween. As showntypically, the internal fluid cavity 49 is formed between upper portion50 and lower portion 52. Upper portion 50 is preferably composed of ahigh thermal conductivity material such as aluminum. The lower portion52 is preferably composed of a low thermal conductivity material such asa suitable plastic to heat isolate the thermal blocks from the rest ofbase unit 12, thereby reducing thermal transfer to other parts of thebase unit and reducing the time required to cool (or heat) the thermalblocks 48 a, 48 b. Base unit 12 remains at or near ambient temperature.

Channels 50 a are cut in upper portion 50 of thermal blocks 48 a, 48 bto receive the metal rods 46 a, 46 b (FIG. 3a) so that when rack 30 a,30 b rests in place at least the lower portion of each of the vials issubstantially surrounded by and in thermal contact with the thermalblocks 48 a, 48 b. The metal rods 46 a, 46 b provide additional thermalconduction between the thermal block and the vials.

If desired, vial storage area 14 can comprise a vial-carrying rotatingcarousel or other known automated vial advancement device in place ofthe vial racks held stationary in storage area 14. The stationary vialracks allow high packing density of the vials over the entire vialstorage area, thereby reducing the cross-sectional area (“footprint”) ofdevice 10 for a given number of vial storage positions. A small devicefootprint is an important consideration in many applications. Further,the use of stationary vial holders simplifies the construction andoperation of device 10.

Turning again to FIG. 2, device 10 includes a vial equilibration station16 that has an upper surface on which a “home” position calibration pad17 is formed or mounted. The pad 17 is centered on the base unit and, aswill be explained, is used for calibrating the position control systemfor the vial transporter 28. The equilibration station 16 comprises fourports 56 a, 56 b, 56 c, 56 d in the base unit 12 where vials can beplaced for a programmable period of time to warm up (or cool down) tothe ambient room temperature. Port 56 c also functions as vialidentification station 18. An outer side wall of each vial can have asticker bearing a unique bar code pattern. An optical bar code readerassembly 58, available commercially and well known, is disposed in baseunit 12 and views the side wall of the vial in port 56 c through avertical slot 60 (partially visible in FIG. 1) in the wall surroundingport 56 c. A rotatable disk 62 is provided at the bottom of port 56 cand is coupled to a stepper motor 64 controlled by a microprocessorbased central control circuit 66. When stepper motor 64 rotates disk 62,the vial resting on the disk 62 rotates until the bar code pattern onthe vial wall is detected by reader assembly 58 through slot 60. Centralcontrol circuit 66 then turns off stepper motor 64.

A vial can be transported by vial transporter 28 from the equilibrationarea 16 or directly from the vial storage area 14 to one of the samplingstations 20 or 22 where sampling operations are performed. At each ofthe sampling stations, a fluid is extracted from the vial. At samplingstation 20, a liquid sample from a liquid specimen is extracted from thevial for subsequent sparging to remove volatiles from the liquid sample.At sampling station 22, a sample in the form of a gas or vapor isextracted from the vial during a sparging operation, preferably afterinjecting a liquid into the vial to contact a. liquid or solid (e.g.soil) specimen, stirring the resulting mixture, and heating the mixture.

The vial transporter 28 is controlled as to position through controlsthat will be explained. In addition to home position calibration pad 17,the position of the racks 30 a and 30 b is preferably measured so theprecise location of receptacles 31, corrected for small shifts of rackposition, is stored in the program. In FIG. 2 one of a pair oforthogonal sensing bars 19 is shown. Each bar 19 is held in position ina respective one of the racks 30 a and 30 b with a pair of plugs 19Athat fit into receptacles 31, specifically receptacles shown at 19 c and19 e. The bar 19 shown is thus held at positions spaced apart in the “X”direction and extend in the “X” direction. The vial transporter uses thebar 19 as a correction or calibration device to calculate the locationof the receptacles 31 of racks 30 a and 30 b with respect to the X and Yaxes.

Vial autosampler device 10 includes one or both sampling modules 24,26,which are adapted to mate with base unit 12 proximate sampling stations20,22, respectively. Advantageously, vial autosampler device 10 can beoutfitted with both or only one of the sampling modules, depending onthe requirements of the user. If outfitted with only one module, theother module can be added to the device later.

FIGS. 4a-4 c show a front, side, and top view of sampling module 24. Aplate 68 has mounting holes 70 for mounting by known means, such asscrews, to base unit 12 such that a projecting face 72 of plate 68 mateswith a rectangular hole in the front face of base unit 12 and is flushwith the surrounding front face of base unit 12. Plate 68 carries a ballscrew 74 mounted on bearings 76,76, and driven by a motor 78 which isalso carried by plate 68. Coupled to ball screw 74 is a vial holderassembly 80 comprising a vial holder cup 82, a spool 84 driven by ballscrew 74, and a connecting arm 86. Ball screw 74 and spool 84 togetherform an elevator which can raise or lower vial holder 82. Limit switches88,90 are carried by plate 68 and contact spool 84 at the lowestposition and highest or raised position, respectively, of vial holderassembly 80. In FIGS. 4a-4 c, vial holder assembly 80 is shown inoutline in the lowest position and is shown in solid lines (and in FIG.4a in cross-section) in the highest position. Vial transporter 28 loadsand unloads a vial into vial holder 82 at the lowest position. As theelevator raises the vial, a needle assembly 92 punctures the vialseptum. Sampling of the vial contents occurs at the highest position,where the needle assembly 92 fully penetrates the vial. Needle assembly92, well known in the art, has an inner needle with a port at its lowertip and an outer needle having a port higher up at point 94. At thehighest position of the vial, the port at 94 remains above the level ofthe liquid specimen in the vial while the tip of the inner needle issubmerged in the liquid specimen. The inner needle communicates withfitting 96, and the outer needle communicates with fitting 98. Inoperation, a volume of the liquid specimen is drawn through the centerneedle and conveyed via fitting 96 to a sparger unit 100 (see FIGS. 1and 10) on base unit 12 or to an external sparger unit.

After a sampling operation, the sample flow path of device 10 permitsflushing of the inner needle of assembly 92, with vial holder 82 raisedand empty, with wash fluid such as water to reduce carryover by cleaningthe inner surfaces of the inner needle. A drain 102 drains the washfluid expelled from the needle.

Plate 68 has a slot 104 (FIG. 4a and 4 b) through which arm 86 extends.The slot 104 has a narrow top portion and a lower portion with cam edgesshaped and positioned relative to ball screw 74 to guide connecting arm86 laterally as spool 84 moves vertically. As a vial and vial holderrise from the lowest position, the arm 86 rides against the cam edge 104a of slot 104. The arm enters the vertical section and the lateralmotion of arm 86 and vial holder 82 is substantially complete when theneedle assembly 92 penetrates the vial septum. When lowering the camedge 104 b of the slot 104 causes the lateral shift to the dottedposition of vial holder 82 in FIG. 4a and 4 c. Other known means such asa separate motor or piston can be used to perform the lateral shift. Camslot 104 and connecting (follower) arm 86 form a simple and reliablemechanism without any additional motor.

A wiper arm 106, on ball screw 74 moves in unison with spool 84 as thescrew 74 turns. As vial holder 82 is lowered after sampling, arm 106pushes down on the vial end cap to strip the needles 92 if frictioncauses the vial to remain. When the vial holder assembly 80 reaches thelowest position, it can be seen in FIG. 4a arm 106 does not shiftlaterally because of its higher position on ball screw 74. The spaceabove vial holder 82 is left free and accessible for loading orunloading a vial.

FIGS. 5a-5 d show detail of sampling module 26. Module 26 has manyelements that have the same function as corresponding elements of module24. These elements include a plate 108, mounting holes 110, projectingface 112, ball screw 114, bearings 116, motor 118, vial holder assembly120, spool 122, vial holder 124, connecting arm 126, limit switches 128(the lower one being hidden behind holder 124 in FIG. 5a), and slot 130in plate 108. Arm 126 extends through slot 130 and engages the edges 130a or 130 b at the lower portion of slot 130 to laterally shift arm 126and a vial carried in vial holder 124. In FIGS. 5a-5 c, the lowestposition of the vial holder (shown in solid lines and cross-section) isthe vial load/unload position, and the highest position of the vialholder (shown in outline) is the sampling position.

As shown, a hollow lower needle 130 c extends through the base of vialholder 120 for puncturing a lower vial septum in a vial 44 having endcaps at both ends. Lower needle 130 c fluidically communicates throughflexible tubing to fitting 132. Vial holder 124 also has a heatingsleeve 134 disposed therein to heat the specimen before or duringsampling. Heating sleeve 134 has electrical power provided by wirescarried on connecting arm 126 to central control circuit 66. Vial holder124 also has a spring-loaded plunger 136 operable to keep the lower vialseptum above the lower needle 130 when a vial is placed in the vialholder until the vial is raised and sampling occurs, and also to forcethe lower vial septum off the lower needle 130 after sampling.

Upper needle assembly 138 has an inner and outer needle similar toneedle assembly 92, but the needles of assembly 138 are shorter so thattheir vent ports remain above the expected level of non-gaseous contentsof the vial shown. The inner needle of assembly 138 communicates withline 140, and the outer needle communicates with line 142.

Sampling module 26 is further equipped with a magnetic sample stirringmechanism 144. Bracket 146 is affixed to plate 108 and holds a stirmotor 148 that turns a primary magnet 150. A bar magnet 152, placed inthe vial prior to loading the vial, is thereby induced to spin, mixingthe contents of the vial. One type of double end vial useable withsampling module 26 is described in U.S. Pat. No. 5,147,551, hereinincorporated by reference, although it is not the only type. Bracket 146includes a spring-loaded plunger 154 (similar to plunger 136) for urgingupper vial septum downward off needle assembly 138.

If either sampling module 24 or 26 is omitted from vial autosamplerdevice 10, a plate can be provided to cover the port on the front panelof base unit 12 that is associated with the omitted module.

Another aspect of the invention is the vial transporter 28. Vialtransporter 28, controlled by central control circuit 66, moves a vialbetween vial storage area 14, equilibration station 16, and samplingstations 20 and 22. Referring now to FIGS. 6a-6 c, vial transporter 28includes a main arm 156 extending along a first (Y) axis 158, a vialgripper assembly 160 adapted for movement along main arm 156, and agripper head 162 which grasps vials by the upper end cap and which canbe lowered and raised from gripper assembly 160. Main arm 156 is adaptedfor movement along a second (X) axis 164, and the motion of gripper head162 relative to gripper assembly 160 is along a third (Z) axis 166. Thefirst, second, and third axes are substantially mutually perpendicular.Vial transporter 28 includes a tray 168 which is rigidly mounted insidebase unit 12 and which supports a suitable circuit board for use withthe arm.

The tray 168 forms a module that can be inserted and removed from thebase unit 12 so that the main arm 156 can be removed and replaced merelyby unplugging the necessary electrical power and signal leads. The tray168 has a front flange frame member 170 that is used for supporting ashaft 172 and pulley 173, driven from a controllable, variable speedreversible arm drive motor 174. The pulley 173 drives a belt 176 that ismounted over an idler pulley 178 mounted on an idler shaft 180 at anopposite end of the tray 168 from the motor. The idler shaft 180 drivesa potentiometer 182 that provides a voltage signal (proportional to itswiper position relative to an end position) indicating the position ofarm 156. Arm 156 clamps to belt 176 in a suitable manner, as shown inFIG. 6b, and moves laterally as indicated by the double arrow 164 as thebelt 176 is driven. Limit sensors 184 and 185 sense position of the arm156 and provide signals used by the controller to stop or reverse themotor 174 when the travel limit is reached.

A motor 202 drives screw 186, rotatably mounted in arm 156, as shown inFIG. 6c, and mounts a suitable drive block 188 that supports the gripperhead 162. A rotating potentiometer 204 driven by screw 186 provides anoutput voltage proportional to its wiper position relative to an endposition of the potentiometer, and this signal also is compared to asignal representing a desired position to provide an error signal todrive motor 202. An indication of the position of the vial gripperassembly 160 along screw 186 (the Y axis) is thus provided.

The Y axis movement also is marked with end limit signals provided by asensor 186 a. Sensor 186 a preferably is a photo-beam sensor comprisinga light emitting diode and a light sensitive transistor spaced from thediode. The sensor 186 a is mounted on a circuit board supported on thedrive block 188. A “flag” 188 f, which is a rail or beam like flatblade, is supported on the arm and is positioned so that the flag 188 fis between the diode and the transistor of the sensor. The flag 188 f isprecisely trimmed as to length and when the gripper assembly moves sothe sensor clears either end of the flag the state of the sensor 186 achanges to provide the end position signal of the gripper assembly.

A gripper head frame 190 is supported on the drive block 188. A drivemotor 192 with an encoder 192 a drives a vertical, rotatable screw 194that threads through a lug 196 fixed to the gripper head 162, to move itvertically as guided by a guide rod 198. Gripper head 162 mountsgripping fingers for gripping the tops of vials and for transporting thevials when the main arm 156 or the gripper assembly 160 is moved.

Referring now to FIG. 6d, a solenoid actuator 200 linearly drives adrive tang 203 in a vertical direction 208. The outer end of tang 203has an annular groove 210 formed therein. A plurality of gripper fingers212 are mounted in a lower end 216 cavity of the gripper head, and areL-shaped, with an actuator end 212 a that fits into the groove 210.There are at least three of the gripper fingers 212, around theperiphery of the gripper head. The fingers are mounted on suitable pivotrods 214 that are fixed in the gripper head 162. The L-shaped gripperfingers 212 have outwardly extending finger ends 212 b that include agrip pad 212 c. Cavity 216 is of size to receive the upper portion andcap of a vial, as shown in FIG. 6d.

The actuator 200 is spring loaded to lift the ends 212 a of the fingers212 to the grip position shown in dotted lines. The finger ends 212 band the grip pads 212 c then grip tightly onto the cap 44 b on the neck44 a of a vial 44, so the vial is lifted by operating drive motor 192through the screw 194.

In FIGS. 6e and 6 f, slightly different ends are shown, which act ashooks under the edges of the caps.

The gripper head includes a sliding plunger 218 connected to a switch orsensor 220. When a plunger end 218 a contacts the upper portion of arack 30 a, 30 b as the gripper head 162 is lowered, the plunger 218 willmove, and a signal will be delivered by the sensor 220 indicating thegripper is down. The actuator 200 is energized so the gripper fingersare open. A second plunger 222 is slidably mounted on the gripper headon the side opposite from the plunger 218, and a sensing foot 224engages the vial cap when a vial is within the gripping fingers 212 c. Asensor 221 is actuated by plunger 222. The actuator 200 can then bede-energized so the fingers 212 pivot under spring load to grip a vial.

The signal from sensor 221, indicating the presence of a vial, enablesthe motor 192 to lift the vial and transport it to the appropriatestation under control of central control circuit 66. The gripper head162 operates to deliver vials to and from the equilibration,identification and respective sampling stations under control of controlcircuit 66. The signal from sensor 221 also indicates that a vial hasbeen released so that the gripper head can be further operated after avial is deposited in a vial holder at a sampling station, for example.The gripper head 162 is a fail safe unit and actuator 200 will remain inits gripping position if there is a loss of power to prevent vialbreakage.

The gripper fingers 212 of the gripper head 162 are surrounded by a vialalignment ring 260 that serves to align the vial and straighten it if itgets slightly cocked when grasped by the gripper fingers. The ring 260,as shown in FIGS. 6d, 6 e, 6 f and 6 g, has a pair of guide cylinders261 on opposite sides thereof, and the guide cylinders 261 in turn mountelongated guide pins 262. The ring 260 has recesses 264 for clearing thegripper fingers 212, and also is provided with openings for the plunger218 and the plunger 222, so that they will operate without interference.

The pins 262 are fixed to cylinders 261 and are slidably received in thebores 263 of guide housings 266 that are mounted onto the gripper head162. The guide housing 266 has an enlarged bore portion 268 that is ofsize to received a long compression coil spring 270 that surrounds therespective pin 262. The spring 270 bears upon the upper surface of thecylinders 261 aligned with their respective housing, and provides aspring force urging the ring downwardly away from the bottom of thegripper head 162.

Also, the upper ends of the guide housing have long larger diameterbores 267 which receives a standoff 269 that thread on the ends of therods 262 to hold the rods on the housing. The standoffs 269 stop travelof the ring 261 as shown in FIG. 6f by engaging a shoulder at the end ofbore 263.

As shown schematically in FIG. 6d, when the gripper head 162 is loweredto engage a vial 44 held in one of the vial racks 30 a or 30 b (rack 30a is shown) the upper surface of the rack will support the ring 261 andthe gripper head moves toward the ring 261 as the springs 270 compress.The plunger 218 is shown engaging the upper surface of the rack 30 a inFIG. 6d as well, so that the sensor 220 has delivered its signal toindicate that the gripper should be actuated for holding the vial 44that is shown. In FIG. 6e the gripper finger shown is in an openposition.

As the vial 44 is lifted from the receptacle 31, that is as the motor192 is driven to raise the gripper head 162, the spring loading from thesprings 270 will cause the alignment ring 261 to separate from thebottom of the gripper head 162, and to surround and slide down along thevial 44 that is being lifted to its stopped position, as limited by thestandoffs 269. This action will tend to keep the vial axis substantiallycoincidental with the central axis of the gripper fingers, and thus thecentral axis of the gripper head 162. If the vial is cocked or slightlyout of position, it will be straightened by the action of the alignmentring 261 so that when it is placed into a receptacle in theequilibration station 16 or one of the receptacles for the samplingstations, the vial will be aligned appropriately so that placement willnot be difficult. A maximum misalignment of only about one degree isallowed. The misalignment is illustrated at 271 in FIG. 6f.

Then, again, when a vial is replaced in a receptacle 31 and the gripperhead 162 moves downwardly, the vial alignment ring 261 will be retractedagainst the action of the springs 270 until such time as the vial isproperly positioned in the receptacle and the plunger 218 is actuated.

As can be seen, the recesses 264 provide adequate clearance for thegripper fingers. The respective plungers for sensing the vial andsensing the rack or tray holding the vials extend through appropriateopenings in the ring.

The nominal position of each vial receptacle 31 for both vial racks ispreprogrammed into the microprocessor control unit 66, in the form of Xand Y coordinates. The potentiometers 182 and 204 give the X and Yposition respectively of the gripper head. There is a gripper up sensor272 that cooperates with a plunger 273 mounted on the arm to provide amaximum up signal when the plunger 273 interrupts a beam in the sensor272. The sensor 272 is a photo beam sensor interrupted by the plunger atthe maximum raised portions.

Referring to FIG. 8, a schematic representation of an access in thefront panel of the base unit is shown, for access to the central controlcircuit 66 has a plug in slot or port 66 a for a removable circuitmodule such as a microprocessor memory card 66 d. An access door 66 bshown in both FIGS. 1 and 11 is provided, to open an opening 66 c in thefront panel of the base unit 12. The opening 66 c aligns with the slotfor the plug in circuit module 66 d that is shown partially removed inFIG. 11, so that for different sampling programs, the memory card ormodule 66 can be removed and replaced with another module. The accessdoor 66 b can have a simple push latch, that will release when pushed,and then latch again when the door is closed. This will permit easymaintenance of various programs for running different samples, utilizingdifferent combinations of the sampling modules that are availablewithout reprogramming.

FIG. 9 illustrates a typical motor circuit that is used in the X and Ydrive motors. The central control circuit 66 includes a microprocessor275 that is programmed appropriately to receive inputs from the varioussensors, such as the sensors 184 and 185 for sensing the end positionsof the X axis, and the sensors 220 and 221 which are used for thepurposes discussed previously.

As stated the Y axis position sensor is provided to signal the end oftravel in each direction of movement of the gripper assembly. The end oftravel signals for the Y axis are provided to the microprocessor 275.The flag 188 f is precision toleranced and is shown in FIGS. 6a and 6 c.

The microprocessor 275 is programmed to include suitable command signalsfor motor energization to drive the motor to move the arm to a desiredlocation. The movement of the arm in the X and Y axes drives a separatepotentiometer as was explained, and for illustration purposes thepotentiometer used with the X axis motor drive is shown in FIG. 9. Thispotentiometer 182 has a voltage reference at one end, and a wiper 182 athat will provide an output signal along the line 276 to a bufferamplifier 277. This voltage is connected to an analog to digitalconverter 278 to provide a digital arm position signal to themicroprocessor 275 along the line 279. The microprocessor 275 providesan output indicating a requested X axis position from the stored programalong the line 282, to a digital to analog converter 283. The invertedanalog output is added to the analog output from the buffer amplifier277 to indicate the actual position along the X axis in FIG. 9. An errorsignal is thus provided along the line 280. This can be suitableamplified with an amplifier 280. The output of amplifier 285 isconnected through a resistor 286 to a motor preamplifier 287.

The preamplifier 287 is used for providing a gain to a motor driveamplifier 290, which ultimately drives the motor, in the showing of FIG.9, motor 174. Preamplifier 287 has a large valve resistor 292 to providea high gain. A first substantially smaller valve resistor 294 isconnected in parallel with resistor 292 through a switch 295 thatfunctions as a “motor-disable” switch controlled by the microprocessor275 when a suitable motor disable signal is sent as represented by block296. A “slow mode” switch and arrangement is also shown: an intermediatevalue resistor 297 is connected in parallel with resistor 292 when aswitch 299 is closed in response to a “slow mode” signal from themicroprocessor 275. This slow mode signal is represented by the box 300.

By way of example, only the resistor 286 may be 2 k ohms; resistor 292may be 100 k ohms; resistor 294 may be 10 k ohms and resistor 297 may be3.3 k ohms, for appropriate operation.

The output of the preamplifier 287 drives the motor drive amplifier 290,whenever a motor enable signal from the microprocessor is received asillustrated by the box 302. The motor enable signal acts through a relay304 that is part of the motor drive amplifier 290. The correct motorrotational direction is a function of the polarity of the signal frompreamplifier 287 so that the motor 174 will be driven either clockwiseor counterclockwise as needed, to reach its desired position.

The exact arrangement shown in FIG. 9 can be used for driving the Y axismotor 202 as well, with the suitable input from the microprocessor 275.

Under microprocessor control, the system is set to provide an initialsequence at startup as an automatic routine, to provide for acalibration of the potentiometer outputs, and also to insure that theinternal lookup tables as to vial positions in the racks or trays isupdated and the correct position for the physical set up that is presentare recorded in the memory. The microprocessor 275 includes lookuptables that provides positions for each of the receptacles 31 in theracks 30 a and 30 b, with respect to a reference position. The referenceposition in the X and Y directions is determined by the calibration pad17, and in particular the edges thereof, as measured by a sensor(plunger 218) on the gripping head at startup.

In addition, the racks or trays have to be correctly orthogonallypositioned. If not positioned correctly, the lookup table values for theX-Y positions have to be compensated so that for example, if the racksor trays are skewed slightly the center axis of each of the vialreceptacles in each row would be slightly different from a defaultposition in both X and Y directions because of the skew.

In order to accomplish the calibration of the system at each start up, aroutine has been programmed in the system to first return the grippinghead to a home position, where the gripper assembly is retracted nearthe base of the main arm, and the main arm is centered on the X axisbetween the sensors 184 and 185. The motor circuits previously describedwould be energized to match a “home” command.

In order to have an accurate position determination of the gripper headin the X and Y axes, the next routine involves determining the scale ofthe feedback potentiometers that are used. For example first, the X axisscale will be calculated by energizing the motor 174 to drive belt 176and move the main arm 156 in a selected direction, toward one of the endlimit sensors. For example, the initial drive could be toward the sensor185 along the X axis. When the sensor 185 indicates that the arm 156 hadreached that end point, the motor 174 is reversed and sent at its normaloperating speed toward the sensor 184. When sensor 184 is reached, atthis point the analog to digital converter value is read by themicroprocessor and recorded in memory. The motor 174 is then reversed,and when the sensor 185 is reached, the microprocessor reads the analogto digital value (which reduces in the reverse direction) and records itin memory. The difference of these values determines the potentiometeroutpout of voltage value per inch of travel, for convenience, calledcounts per inch, using a software driven algorithm.

For even more precision a target position or value can be selected andthe count from the A/D converter from a reference position to the targetis determined and compared to the target value count. The arm can thenbe moved past the target position to another known start position andreversed so the count to the target coming from the reverse direction isalso determined. Differences in the count resulting from the differentdirections of travel can be averaged to provide a more accuratecalibration of the X and Y offset.

For example, if it is known that the distance between the sensors 184and 185 is ten and one half inches, (and that does not change) thenumber of counts from the actual position signal from the potentiometeris used for adjusting and updating the scale counts per inch in theoperating software so that the X requested position (provided bysoftware) is in harmony with the position provided by the potentiometer.The calibration procedure at every start up to correct for changes inthe potentiometers permits the use of potentiometers for positiondetermination, rather than more expensive digital encoders.

Additionally, after calibration in the X axis, the arm 156 is moved toits center or home position in accordance with the program in themicroprocessor, and the motor 202 is then energized to cause thegripping head to travel along the screw 186 so that the sensor 186 apasses one end of flag 188 f. The motor 202 is reversed and the voltagefrom the potentiometer is converted and when the opposite end of theflag 188 f is reached the value is stored in memory. The motor 202 isagain reversed and the micro processor reads the analog to digitaloutput of the potentiometer 204 until the first end of the flag 188 f isagain reached. The difference of the values from the potentiometerdetermines the counts per inch of travel, through a software algorithm.This calibration routine can be initiated by operator input at thekeypad as well.

The gripper mechanism is then lowered by energizing motor 192 until theindicator or plunger 218 rests on the top of the pad 17. The tolerancesof the system are such that bringing the gripping head back to this homeposition is generally within tolerance so that the end 218 a of theplunger 218 will rest on the top surface of the calibration pad 17.

The arm motors are then operated, when the plunger end 218 a is ridingon the surface of the calibration pad 17, at the slow rate of motoroperation, that is in a slow mode, along the X axis until the plunger218 drops off the sharp edge of the calibration pad 17. The calibrationpad 17 is made with vertical walls and sharp edges (non chamfered) sothat there is an abrupt change of position of the plunger 218 as itmoves in the X axis. This is a known position that the edge of thecalibration pad 17 which is used to update the home position in the Xdirection for the arm 156. The calculation from the edge to the centerof the calibration pad 17 is done by software update.

Then, once the plunger 218 is returned to the center of the pad 17 or tosome other home position that is known, the Y axis motor 202 isenergized in a slow mode and the gripper head is moved along the screw186 until the plunger 218 again drops off an edge of the calibration pad17. The controls have a known position in the Y direction to use as areference and to update the software for determining the home orreference position for the arm. The home reference is the reference fromwhich the X-Y position of each of the vial receptacles is set in thelookup tables. Of course, when the unit is moved so that the plunger 218is placed back onto the pad 17, the gripper head motor would be drivento raise the plunger 218 sufficiently so that it would not catch theedge of the calibration pad 17 and then subsequently relower before theY axis calibration is made.

The steps of this program are illustrated in FIG. 10. In the program thefirst step is to obtain the X and Y offset values for the actualoperation, which are the differences in each axis between thetheoretical X, Y coordinates of a location, such as the home position,that is preprogrammed in the look up table provided, and the measuredposition as determined by the output of the potentiometers. Thetheoretical or target are default values, and are based upon thetheoretical position in the X,Y coordinate system from the originallayout. This step is illustrated in block 308. The offset values areused to establish corrections for a working look up table inmicroprocessor memory. The calculated X scale is shown at 305, and thecalculated Y scale is shown at 306, which are them established. Thesevalues are obtained as previously described to obtain the counts perinch in each of the axes. The interrupt in the sequence is at the timethat the gripper head is moved to its home position on the calibratingpad 17.

Then the measuring of the calibration pad values illustrated at 307 isas described. The X offset and Y offset are used to correct the defaultor theoretical home position to establish a corrected home position forthe X edge and Y edge of the calibration pad 17, respectively.

After that is done, and the new default home position has beenestablished in the software, each of the trays or racks 30 a and 30 b isinspected, using the calibration bar 19 that was previously explained,for orthogonal positioning to make sure that the rows of vialreceptacles are parallel to the X axis, or, if offset or skewed, make acompensating adjustment in the software and updating of the defaultpositions lookup tables for each of the receptacles. Referring to FIG.2, where the orthogonal calibration bar 19 is shown in only one of thetrays or racks for the vials, for illustrative purposes, the main robotarm 156 would be driven in an X direction to a location laterally thatwould be close to one of the ends of the calibration bar 19, and thenthe gripper head 162 would be driven along the screw 186 to a locationwhere the plunger 218 would rest on the ton of the calibration bar 19.That could be done for example by providing the X-Y coordinates from thesoftware lookup table for the receptacle illustrated at 19 c in FIG. 2which supports one of the plugs 19 a.

Then by moving the gripper head 162 back toward the base of the main armuntil the plunger 218 drops off the sharply defined edge of the bar 19that is shown at 19 b, a first reference distance from the home positionin the Y direction can be obtained for the lookup tables. Theinformation will be stored until the opposite end of the calibration bar19 is inspected for example, adjacent the receptacle shown in dottedlines as 19 e. The gripper head is raised, moved laterally to the endadjacent the receptacle 19 e and then lowered down so the plunger restson the top of the bar 19, after which the gripper head is retractedtoward the base of the arm until the plunger 218 drops off the edge 19 dadjacent the receptacle 19 e. This position information is recorded andcompared to the information for the position of the edge 19 d adjacentreceptacle 19 c. By comparing these values, the skew or orthogonalitystatus of the rack or tray that has been placed on the support 12 isdetermined. Also the value of the Y distance to the bar and thus thetrays is provided for update, if needed. Appropriate compensationfactors can be placed into the lookup table to clearly establish thepresent position of each of the receptacles for holding the vials.

The X position of the receptacle in each tray or rack 30 a or 30 b thatis the distance in the X direction from the arm center position can beestablished by using the gripper head plunger 218 to sense the ends ofthe bar 19 at the corners of the bar. The skew and the actual X-Yposition of the receptacles in thus obtained. While the bar isillustrated only in tray 30 b in FIG. 2, the bar 19 would also be usedto calibrate the positions of the receptacles in the tray 30 a as well.In FIG. 10, this step is illustrated at blocks 309, 310 and 311.

Also as shown in FIG. 2, the equilibration receptacles or stations 56 a,56 b, 56 c and 56 d have known theoretical or default X-Y coordinatepositions stored in software, and the positions of these receptacles inrelation to the operation of the present device is updated. The watermodule and soil module vial receptacles, which will be loaded with therobot arm also have known positions and in the vial loading position ofeach of the modules as shown in FIG. 2, will be updated in the softwareas to their X-Y locations taking into account the calibration sequencejust described. This step is illustrated in box 312.

It should be noted that the updating of the lookup tables can be done ona “global” scale where the lookup tables are updated immediately uponcalculation of the X and Y axes offsets, and used as a working look uptable or the correction factors can be added into the output of thelookup tables for each vial receptacle 31, as well as for the otherreceptacles 56 a-56 d and the soil and water module vial holders onlyduring the time when a particular vial receptacle is to be reached.

FIG. 11 provides a flow diagram generally outlining the softwareoperations in the microprocessor 275, for operations as just described.The first step again is to calibrate the scale of the X and Y movements,in counts per inch or other unit of measurement as shown by the block318 so the correct values will be provided for the subsequent functions.

There is in the memory of the microprocessor and software a default,target or theoretical present value in a lookup table for each of thevial positions for the receptacles 31 of each of the trays or racks andthe other receptacles for vials provided. That is indicated at box 320.The X axis offset and the Y axis offset are calculated for positioninformation, as shown by the block or box 336.

Also, the software contains the positions (box 322) of the traycalibration bar 19 for each of the two trays or racks 30 a and 30 b, andthey would have default values in the X and Y directions for the ends ofthe bars 19 such as that shown adjacent receptacle 19 c and adjacentreceptacle 19 e. It is to be understood that a similar bar would be usedon the other tray or rack. The X-Y positions measured for the two endsof bar 19 as sensed by the plunger 218 are illustrated at block 322.

The calibration pad 17 has default position values as illustrated inblock 324, including the start point position, which would be theuncalibrated “home” position to which the unit would be returned forcalibration, and the X edge and Y edge positions in the X and Ydirections, respectively, which is a mechanical position used forestablishing the reference point. There would be default positions inthe X and Y directions for the stations 56 a-56 d, and the water moduleand the soil module vial holders as illustrated in the block 326.

The measured tray calibration bar values for the Y direction edge 19 dadjacent the receptacles 19 c and 19 e, respectively. Additionally, theends of the bar 19 are used for location of the calibration bar 19 inthe X direction, if desired. The end 19 f adjacent the receptacle 19 ccan be sensed for positioning and skew in the X direction using theplunger 218, and programming the gripper head to move over that edgeadjacent the corners so that the plunger would drop off the edge. Theend edge 19 g adjacent the receptacle 19 e can be sensed by having aplunger to move to that edge and drop over the edge as well. Thisprocedure of calibrating the position of the racks or trays and theorthogonality or orthogonal positions of the rows of the vialreceptacles 31 shown in block 328.

After measurement, the calculated values for correction shown at block330 for the orthogonality and the X-Y positions of each vial receptacle31 are obtained.

The memory will correct the lookup table using the offset values fromblock 336 and other needed calculated values for orthogonality fromblock 330 and provide a working vial position lookup table indicated bythe block 332, (if the default values were not corrected each time theywere needed and retrieved). In other words there would be a working vialposition lookup table generated in the software for the particularsequence of operations to be performed after the initial start upsignal.

The calibration pad 17 default values from block 324 would be adjustedby measuring the values at the X edge and the Y edge as indicated by theblock 334 and this information is used for the tray calibrationfunctions of block 322.

The theoretical or default values for the stations 56 a-56 d, the watermodule, and soil module would be provided as indicated by block 336 andthese values are adjusted with the offset values from block 336 and thecalculated calibration pad values from block 334 to establish a workingposition table for the stations, and for the water and soil modules.

The robot arm would then be set to operate in a preprogrammed routine,or if desired, an individual sequence could be operator keyed in so thatany particular vial in any of the receptacles 48 a and 48 b could beexamined in sequence by lifting the vial, moving it to one of thereceptacles 56 a, 56 b, 56 c and 56 d and subsequently as desired intothe soil or water modules for analysis.

It can be seen thus that a position reference is provided at the “home”position, and in relation to a stored default controlled location thepositions of the vial receptacles are provided. The actual position ofthe home is measured, by measuring the edges of the calibration pad, andthe differences between the stored or default home position and theactual position or measured position are calculated, and then acorrected position of the vial holding stations is calculated as afunction of the default position for that station and the differencesthat are calculated relating to the home position. The robotic arm isthus then operated and moved to the desired vial holding station as afunction of the corrected or calculating position.

FIG. 7 schematically illustrates one arrangement used for samplingliquid or water samples in the station 20. Other sequences can beprogrammed for use with soil samples. Once a vial has been properlyidentified using the bar code reader, and equilibrated, and is placed bythe vial transporter 28, into the cup type vial holder 82 of samplingmodule 24, sampling a liquid or water sample is conducted using thefluid circuit of FIG. 7. A sequence of operations for various functionsis set forth in Table I, for simplicity of understanding of actuation orstates of the various valves and other components.

In all of the sequences that are illustrated, it is important to notethat the system permits backflushing the needles with a water or liquidto remove previous sample traces, utilizing the cup type vial holders tocollect the backwash liquid and drain it as previously discussed andshown. A multi port chromatograph valve is utilized to permitselectively adding a known volume of two different standards into thetest sample.

The samples are transferred to a purge and trap concentrator to purgethe volatiles into a sorbet trap, which is then heated and swept with acarrier gas into a gas chromatograph column for separation anddetection. Thus the outlet conduits labeled “to concentrator” means thatthese are connected to existing instruments that are well known forprocessing and subsequent analysis. A Model 3000 purge and trapconcentrators made by Tekmar Company of Cincinnati, Ohio is useful orthe spraying unit 100 can be used.

The water module connections and piping are shown generally at 230 andare outlined in dotted lines as are components on the base unit 12. Asource of water 232, helium 233 and lines with pressure regulators 234and flow controllers 235 are provided.

On-off valves C and D control a source of helium 233. Valve D connectsto the outer needle assembly 92 in a water sample vial 42 held in vialholder 82. Valve C connects through a valve L to a solenoid operatedmultiple port valve P5 operated to four different connections inresponse to control signals to connect any two adjacent valve ports. Forexplanation purposes, the valve P5, also shown in FIGS. 1 and 7a, has afirst position P5A that connects the ports 1 and 2; a second positionP5B that connects ports 2 and 3; a third position P5C that connectsports 3 and 4, and as shown in FIG. 7 a fourth position P5D connectingports 4 and 1. This valve is a conventional valve that has a centerblock that will connect the adjacent ports as desired by moving to thepositions P5A, P5B, P5C, and P5D.

Port 2 of valve P5 is connected to a commercially available syringe pump238 (See also FIG. 1) which has an inner plunger that is driven by anexternal motor 239 of any desired form. The syringe pump 238 receivesand discharges samples under control of motor 239 when valve P5 is atits desired location.

Valve L connects to port 4 of valve P5, and port 1 is connected througha filter 239 to a valve J connected to the inner (sampling) needle ofneedle assembly 92 in vial 42. Valve I leads from the water source 232to a “t” connection between filter 229 and valve P5. Valve L also has aport connected to the water source 232.

The port 2 of P5 connects to the outlet of the syringe pump 238. Port 3of P5 connects to a port of a multi-port chromatographic valve X6, usedfor adding a known volume of a standard into a sample that is deliveredto a concentrator such as the purge and trap concentrator.

A first standard source vial 240, and a second standard source vial 242are fluidly coupled by conduits through valves E and F, respectively, toseparate ports on valve X6. These vials can be used for providingmatrix.

The multi port chromatographic valve X6 is a stepper type rotarysolenoid valve that has an internal block that can be rotated 90° andwhich has two schematically shown U-shaped internal channels X6-1 andX6-2 (see also FIG. 7b). Channel X6-1 connects the internal standardsource 240 port to the port leading to valve H which leads to drain.

In FIG. 7 U-shaped channel X6-2 connects port 3 of valve P5 through aport of X6 to line 244. Valve X6 rotates 90° counter clockwise undercontrol of circuit 66 and then as shown in FIG. 7b, channel X6-2connects the surrogate standard source 242 to valve H. The U-shapedchannel X6-1 then connects port 3 on valve P5 to line 244. Those are thetwo operable positions of valve X6.

The sequence of operation is shown in Table I below. In Table I theindividual valves designated by capital letters are considered to havetwo positions. “0” designates off, and “1” equals on, in the tablecolumns. The P5 valve connections or positions P5A-P5D, are designatedby the letter (A-D) in the table column.

Valve X6 is indicated by position A shown in solid lines in FIG. 7, andin position B it is rotated 90° and shown in FIG. 7b. Additionally, incertain instances, the “vial mechanical position” column shows whetherthe vial holder and vial is up (U) (pierced by the sample needle) ordown (D).

TABLE I Water System - Water Module Only Vial Mode of Mech Operation C DE F H I J L pos. X6 P5 STANDBY AND 0 0 0 0 0 0 0 0 D A D WAIT FOR PURGEREADY PREPURGE 1 1 0 0 0 0 0 0 D A D RAISE VIAL 0 0 0 0 0 0 0 0 U A DFILL SYRINGE 0 1 0 0 0 0 0 0 U A A FILL STD. 1 0 0 1 0 1 0 0 0 U A ATRANS 0 0 0 0 0 0 0 0 U B B SAMPLE STD 1 SWEEP TRANS 1 0 0 0 0 0 0 0 U AC LINE FILL STD 2 0 0 0 1 1 0 0 0 U B D TRANS 0 0 0 0 0 0 0 0 U A BSAMPLE STD 2 SWEEP 1 0 0 0 0 0 0 0 U A C TRANS LINE RINSE 0 0 0 0 0 1 10 U A A SYRINGE DRAIN 0 0 0 0 0 0 1 0 U A A SYRINGE BACKFLUSH 0 0 0 0 01 1 0 U A C FILTER RETURN VIAL 0 0 0 0 0 0 0 0 D A C TO TRAY FLUSHING 00 0 0 0 1 0 0 U A C NEEDLE WAIT FOR 0 0 0 0 0 0 0 0 D A D DESORB RINSE 00 0 0 0 0 0 1 D A D GLASSWARE PURGE 1 0 0 0 0 0 0 0 D A C GLASSWARE

At the cycle start (standby) and waiting for a purge ready signal fromthe concentrator or other instrument that it is ready to receive asample the components are in the same condition. The vial is down, andvalve P5 is in the solid line position P5D. In the prepurging stage,valves C and D open, and helium is provided through valves D, L, P5, andJ to flow out the needles. The vial is raised to engage the needle, withthe valves all closed. Filling the syringe as the syringe plungerretracts has valve D open and valve P5 shifted to position P5Aconnecting port 1 to port 2 to the syringe 238.

Standard filling is by opening valve H and valve E. Channel loop X6-1fills with standard 1. Standard in loop X6-1 and one half of the sampleare transferred by moving valve X6 90° to position “B” to connectchannel X6-1 between valve P5 in position P5B and line 244. The syringeor pump 238 discharges ½ the sample through the valve X6 and line 244,carrying with it the quantity of standard 1 in channel X6-1 to line 244and the concentrator.

Standard 2 is filled by moving valve P5 to position P5D, opening valvesF and H (to drain) so a quantity of standard 2 fills loop X6-2.Transferring standard 2 occurs with valve P5 moved to position P5B,valve X6 moved to position A, and the remaining portion of the samplecontained in the syringe or pump 238 discharged by motor 239 throughloop X6-2 into line 244.

The two halves of the sample, and the different standards, (which can beselectively added) have thus been sent to the concentrator, for handlingand for subsequent analysis. The transfer line is swept as valve C opensand valve P5 moves to the P5C position, connecting valve L to valve X6and thus to line 244 for flushing through valve X-6.

The syringe is rinsed with water; valve I is open, valve J is open (todrain) and valve P5 is moved to the P5A position. The syringe isretracted to fill with water.

The syringe or pumper 238 is then drained by shutting off valve I butleaving valve J connected to drain and moving the syringe plunger up.The filter is backflushed by opening valves I and J and moving valve P5in its P5C position.

The vial is lowered by operating the vial elevator and the vialtransporter removes the vial from holder 82 and returns it to the tray.The vial holder 82 is preferably raised again and the inner needle isflushed with water by opening the valve I and leaving valve P5 in theP5C position. Water will flush through the inner needle to insure nocarryover and will be contained and drained from the vial holder.

The needle may be purged if desired, through P5 by opening valve C withvalve J off. While waiting for a desorb signal from the concentrator ortest apparatus, the unit is essentially at rest with the valve P5 in itsposition P5D. The glassware conduits are liquid rinsed by opening thevalve L to the water source, and connecting through valve P5 and valveX6 to line 244. The vial holder is down for reloading a vial. Helium ispurged through the glassware by opening valve C after closing valve Land moving P5 to position P5C.

The cycle will then repeat, as desired for each additional vial that islifted in the appropriate station for the water module.

It should be noted that if only one of the standards is injected intothe sample per run, movement of valve X6 will place one of the channelsX6-1 or X6-2 open to the other standard source, and such channel maythen be flushed clean during the desorb cycle. The appropriate channelX6-1 or X6-2 is between valve P5 and line 244 during the syringe rinseand purge cycles.

Utilizing the soil module 26 is similar to that shown in FIG. 7 but willuse a double ended vial 44, with a lower needle 130 and an upper doubleneedle assembly. A single ended vial can be used. The valves andconnections are selected to accommodate the needed functions for soilsample analysis.

The central control unit 66 is a standard programmable unit, such as amicrocomputer or microprocessor that will accept inputs, including theneeded limit sensors or limit switches for the soil module, and thewater module indicating the limits of travel for the vial holders, adata entry keyboard, so that particular operations can be keyed in by anoperator, inputs for the two switches indicating the vial racks are inposition, limit switches for the x and y directions for the transferarm, the two plungers on the gripper head for indicating positionadjacent vial racks, and whether a vial is held in the gripper head.Three potentiometer inputs comprising encoders for the arm movement,including an encoder on the vertical moving drive for the gripper head,and bar code reader input for reading signals from the bar code labelsfor vial identification in handling are included.

The outputs would include operation of the pump or syringe motor 239,each of the solenoid valves that are shown in FIG. 7, the x, y, and zmotors for the arm 156 as well as the actuator 200 for the gripperfingers, a motor for the rotating disc 62 at the bar code reader, themagnetic stir motor, and the elevator motors for the soil and watermodules, respectively, as well as an output for the heater. All of theseoutputs can be provided in a desired sequence that can be preprogrammedinto the unit, or modified by the data entry keyboard.

Such a programmable unit for the central circuit 66 is well known, andcan form any desired type. The operations are sequential, so that thestate of various solenoid valves and other operators are changed uponthe completion of previous operations in the sequence. The x-y locationof the vials in the vial racks can be programmed in, and the positioningof the vial holders for the soil and water module also can bepreprogrammed in so that as instructions are given the vial transferapparatus 28 will go to the proper location. The control sequences aremore fully explained in connection with FIGS. 13, 14 and 15.

Modular operation is obtained, with a soil module, a water module orboth. The additional valves also can be added with the modules. Valve X5would be added to the base unit when both modules are used.

The water samples can be waste water or drinking water and rods orsludges can be handled. The bar code reader keeps track of the vials andsamples, throughout the test and the controls can insure the results areattached to the proper sample by the bar code use. The bar code readerforms an input to control module 66 and control module can be used tocorrelate analysis with the appropriate vial. The cooling function forthe vials is built into the base unit for convenient and proper testsequencing.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A vial autosampler, comprising: a vial storagestation; a vial sampling station; and a robotic arm operable totransport a vial between the vial storage station and the vial samplingstation, the robotic arm having a gripper head for grasping the vial;wherein the robotic arm further includes a stabilizing member that isspring loaded to the gripper head, and extendable from the gripper headin close proximity to the vial to reduce pivoting of the vial duringtransport.
 2. A vial autosampler, comprising: a vial storage station; avial sampling station; and a robotic arm operable to transport a vialbetween the vial storage station and the vial sampling station, therobotic arm having a gripper head for grasping the vial; wherein therobotic arm further includes a stabilizing member extendable from thegripper head in close proximity to the vial to reduce pivoting of thevial during transport; and wherein the stabilizing member movably mountsto the gripper head such that the stabilizing member retracts toward thegripper head as the gripper head approaches the vial.
 3. A vialautosampler, comprising: a vial storage station; a vial samplingstation; and a robotic arm operable to transport a vial between the vialstorage station and the vial sampling station, the robotic arm having agripper head for grasping the vial; wherein the robotic arm furtherincludes a stabilizing member extendable from the gripper head in closeproximity to the vial to reduce pivoting of the vial during transport;and wherein the stabilizing member comprises a ring having an innerdiameter which is sized to the exterior of the vial.
 4. The vialautosampler of claim 3, wherein the ring couples to the gripper head byat least one spring-loaded rod.
 5. A vial autosampler, comprising: avial storage station; a vial sampling station; and a robotic armoperable to transport a vial between the vial storage station and thevial sampling station, the robotic arm having a gripper head forgrasping the vial; wherein the robotic arm further includes astabilizing member extendable from the gripper head in close proximityto the vial to reduce pivoting of the vial during transport; and whereinthe stabilizing member further has notches therein opening to the innerdiameter to accommodate the grasping operation of the gripper head.